This invention has relation to machines for magnetic recording and playback of data on a plurality of parallel tracks of a record medium such as a moving magnetic tape, and particularly to a subassembly of such a machine for moving record/playback heads transversely of the direction of movement of the magnetic tape to align such heads with various of the magnetic tracks on the tape.
The problem and importance of aligning record tracks on magnetic mediums with composite magnetic cores is discussed in U.S. Pat. No. 4,300,179 granted to Barnes and von Behren on Nov. 10, 1981 in the Background of the Invention at column 1, beginning on line 10.
The importance of maintaining contacts between the record medium and the magnetic head and of providing support for the record carrier or tape as the magnetic head is laterally aligned with various recorded tracks on the tape is discussed in this same patent to Barnes et al at column 2, paragraph beginning on line 5.
There is a problem growing out of the necessity of assembling an entire magnetic head, including the core windings, before testing; and then, after testing, having to, oftentimes, throw away the entire head if the testing shows that it is faulty. This problem is likewise discussed by Barnes et al at column 2, paragraph beginning on line 21.
When magnetic head assembly of the prior art was assembled, tested, installed for use and subsequently a coil winding failed, the entire housing for the head assembly had to be torn down and replaced. Barnes, supra, column 2, beginning on line 27.
This Barnes et al patent presents a composite magnetic head with multi-track support structure which gives good support to the entire transverse width of the magnetic tape as magnetic head and the entire support structure moves up and down in contact with the horizontally moving tape. To accomplish this, a yoke 20 supports record/playback heads 10, 12 and 14 and provides a top surface 22 having the same scrub path as these heads. Because the entire yoke moves with the heads, to support the magnetic tape at all times, the yoke "extends in both directions transversely of the record carrier at least a distance equal to width of the record carrier in each direction." Abstract of Barnes, supra and FIG. 4.
This movement of the yoke 20 of Barnes et al transversely of the record carrier as the record carrier moves on its path, necessarily causes more scrubbing action of the carrier on the center portions of the yoke than on either end portion, since each end portion is, at least part of the time, not in touch with the moving record carrier. For this reason, the wear of the yoke is uneven. Such non-uniform wear of the yoke results in the record carrier running on a surface which is not flat and this disturbs the needed smooth and even contact between the moving carrier and the magnetic head(s).
By this reference, this patent to Barnes et al, U.S. Pat. No. 4,300,179, granted Nov. 10, 1981, is incorporated into this specification and made a part of this disclosure.
Because of the need to move the entire yoke substantially twice the width of the record carrier in direction transverse to the direction of the record carrier tape movement, the overall height of the multitrack support structure was a continuing design problem in an environment where miniaturization has become increasingly important.
Other patents which are related to this invention are U.S. Pat. No. 4,686,596 granted to Kraemer and Iverson on Aug. 11, 1987; U.S. Pat. No. 4,658,314 granted to Sasazaki on Apr. 14, 1987; U.S. Pat. No. 4,322,764 granted to Tamaka on Mar. 30, 1982; U.S. Pat. No. 4,313,143 granted to Zarr on Jan. 26, 1982; U.S. Pat. No. 3,692,255 granted to von Behren on Sep. 19, 1972; and U.S. Pat. No. 3,539,191 to Yamamoto on Nov. 10, 1970.
What was not present before the present invention was a subassembly which provided stationary structures to come into contact and support a longitudinally moving magnetic tape over its entire transverse width on both sides of composite magnetic heads which are in contact with the magnetic tape and are being moved transversely to the direction of movement of the tape.
Also needed was a structure in which failure or excessive wear of magnetic cores can be overcome by removal and replacement of a moving head holder and its magnetic core(s) without the need for replacing the entire multitrack support structure or housing apparatus. Additionally, to achieve further miniaturization, a housing apparatus was needed that was closer to the transverse width of the record medium magnetic tape being used, and not to twice that width.